Our objective was to isolate peptidases from the latex of Maclura pomifera fruits and use them to hydrolyze food proteins, as well as to purify and characterize the main peptidase. Two partially purified proteolytic extracts were prepared by ethanol (EE) and acetone (AE) precipitation from an aqueous suspension of exuded fruit latex. EE was used to hydrolyze food proteins with a ratio of 0.19 caseinolytic units (Ucas) per mg of substrate. Different values of hydrolysis degree were observed for hydrolysates of egg white, soy protein isolate, and casein at 180 min (9.3%, 31.1%, and 29.1%, respectively). AE was employed to purify a peptidase which exhibited an isoelectric point (pI) of 8.70 and whose abundance in AE was 28.3%. This enzyme was purified to homogeneity using a single-step procedure by cation-exchange chromatography, achieving an 8.1-fold purification and a yield of 16.7%. The peptidase was named pomiferin I and showed a molecular mass of 63,177.77 Da. Kinetic constants (K_M 0.84 mM, V_max 27.50 uM s⁻¹, k_cat 72.37 s⁻¹, and k_cat/K_M 86.15 mM⁻¹ s⁻¹) were determined employing N-α-carbobenzoxy-L-alanyl-p-nitrophenyl ester as substrate. Analysis by PMF showed only partial homology of pomiferin I with a serine peptidase from a species of the same family.

我们的目的是从绒毛Maclura乳胶中分离肽酶水果并使用它们来水解食物蛋白，以及纯化和鉴定主要的肽酶。通过从渗出的水果胶乳的水悬浮液中进行乙醇（EE）和丙酮（AE）沉淀制备两种部分纯化的蛋白水解提取物。EE用于水解食物蛋白质，每毫克底物的比例为0.19酪蛋白分解单位（Ucas）。在180分钟时，蛋白，大豆分离蛋白和酪蛋白的水解物观察到不同的水解度值（分别为9.3％，31.1％和29.1％）。AE被用于纯化肽酶，其表现出等电点（pI）为8.70并且其在AE中的丰度为28.3％。通过一步一步的阳离子交换色谱法将该酶纯化至均质，纯化率达到8.1倍，收率达16.7％。该肽酶命名为pomiferin I，分子量为63,177.77 Da。动力学常数（K使用N-α-碳苯甲氧基-L-丙氨酰-对硝基苯酯测定_M 0.84 mM，V _max 27.50 uM s ^-1，k _cat 72.37 s ^-1和k _cat / K _M 86.15 mM ^-1  s ^-1）作为基材。PMF的分析表明，pomiferin I与来自同一科种的丝氨酸肽酶仅部分同源。